We've mostly only used a strap on, but want to experiment with only massage to try and achieve an orgasm. Any helpful hints?

Make sure his bladder is empty and all that. I would try to make sure he is warmed up i can use a lucid dreamer vibrator to stimulate my prostate. But you are supposed to be able to reach it with your fingers neither of us can reach it with out a toy. Whether you are going to use a toy or a finger you will need to angle toward his navel inorder to brush up against the prostate. I think you might need to experiment and just kind of explore with a toy or finger and have your guy tell you when you hit the spot. Its kind of like a peeing sensation but its not the same he will know the difference.

Yeah, empty bladder, empty bowels, deep sense of relaxation. It would probably help if he went a couple days without orgasm beforehand as well. Then just be patient. It might not happen the first, second, third times ...

Has he noticed a point where it feels REALLY GOOD deep inside him, like at the base of his penis but inside? That's where the good times are. You and he will need to find a way to hit that spot.